AT&T announced early on that users wouldn’t be able to use FaceTime over cellular connections on its network, for subscribers who aren’t on the carrier’s Mobile Share Plans. The decision was obviously not popular with users; it took long enough for Apple to make FaceTime even available over cellular data connections, and AT&T subscribers were hearing they’d be left out. But they aren’t the only ones angered by the decision. Today, Free Press, Public Knowledge and the New America Foundation’s Open Technology Institute have announced (via GigaOM) that they’ll be filing a formal complaint with the FCC about the block.

Basically, AT&T’s position is that since the FaceTime app comes preloaded on iPhones, they aren’t in the wrong. Since AT&T doesn’t restrict users from downloading any apps that compete with its own voice or video chat services, it believes that it technically abides by the letter of the FCC’s net neutrality rules. That’s not exactly a response that likely finds a lot of sympathy among AT&T users who won’t get the full iOS 6 experience when it arrives tomorrow.

It’s apparent that Public Knowledge and the other organizations who posted this letter notifying AT&T of the intent to file also didn’t buy it. Here’s the meat of what they provided the carrier today:

We respectfully request that AT&T reconsider its behavior and the impact that blocking FaceTime will have on its customers, particularly the deaf and hard of hearing, as well as all who use this application to communicate with family and friends over the Internet. Making mobile use of the application available only to those customers who pay for unlimited voice and text messages harms individuals and innovation alike. We ask instead that AT&T make this core feature of the popular iPhone and iPad devices available to all of its customers, in compliance with the Open Internet rules that “preserve the Internet as an open platform enabling consumer choice, freedom of expression, end-user control, competition, and the freedom to innovate without permission.

FaceTime admittedly probably represents a large potential threat in terms of mobile network infrastructure and bandwidth demands, but it’s hard to not see this as a way to encourage users to sign up with more expensive Mobile Share Plans. We reached out to AT&T for comment, and will update when we hear back with the carrier’s official response on the matter.